Optically active benzene derivatives, process for producing the same and liquid-crystalline substances containing said derivatives as active ingredient and optical switching elements

ABSTRACT

Disclosed are novel active benzene derivatives represented by the general formula (I): ##STR1## (wherein X represents --COO--, --OCO--, --CH 2  O-- or --OCH 2  --; A represents a hydrogen atom, a halogen atom or an alkyl or alkoxyl group having 1 to 20 carbon atoms: R represents an alkyl group having 1 to 20 carbon atoms; l and m each represents a number of 1 or 2, n represents a number of 0 or 1, but when n is 0 the sum of l and m is 3 or less; and * indicates asymmetric carbon atom), a process for producing the same, liquid-crystalline substances containing said derivatives as active ingredient, and optical switching elements utilizing the liquid crystal compositions containing said liquid-crystalline substances.

This is a division of application Ser. No. 07/986,871, filed Dec. 4,1992, now U.S. Pat. No. 5,274,168, which in turn is a continuation ofapplication Ser. No. 07/589,500, filed Nov. 9, 1990, now abandoned,which in turn is a division of application Ser. No. 07/170,409, filedMar. 18, 1988, now U.S. Pat. No. 5,002,693.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the optically active benzene derivativesrepresented by the general formula (I): ##STR2## (wherein X represents--COO--, --OCO--, CH₂ O-- or --OCH₂ --; A represents a hydrogen atom, ahalogen atom or an alkyl or alkoxyl group having 1 to 20 carbon atoms; Rrepresents an alkyl group having 1 to 20 carbon atoms; l and m eachrepresents a number of 1 or 2, n represents a number of 0 or 1, but whenis 0 the sum of l and m is 3 or less; and * indicates asymmetric carbonatom), a process for producing the same, liquid-crystalline substancescontaining said derivatives as active ingredient, and optical switchingelements utilizing the liquid crystal compositions containing saidliquid-crystalline substances.

The term "liquid-crystalline substances" is used in this specificationto refer to the liquid-crystalline substances of the broad sense,including those which may not have been confirmed to take a liquidcrystal phase per se but can be utilized effectively as a liquid crystalcomposition.

2. Prior Art

Image display devices using liquid crystal are now practically used invarious fields. Twinsted nematic type liquid crystal display is known asone of these display systems. This display system has the advantagesthat its power consumption is low and it is soft to the eye because ofthe light-receiving type (the display panel itself is not luminous).Display by this system, however, is not always satisfactory in theaspect of response speed.

As a system which is capable of high speed response, a display deviceutilizing the optical switching performance of ferroelectric liquidcrystal has been proposed (Applied Physics Letters, 36, 899 (1980)) andis attracting attention.

In view of its molecular configuration, ferroelectric liquid crystal isconsidered to belong to the type of liquid crystal having chiral smecticC phase (hereinafter referred to as S_(C) * phase) or chiral smectic Hphase (S_(H) * phase). With its high speed response characteristics,such ferroelectric liquid crystal is expected to find its use not onlyfor display devices such as liquid crystal televisions but also asmaterials for electronic elements such as optical printer head,photo-Fourier transformation element, etc.

Such known liquid crystal compounds, however, had problems in practicaluse such as poor stability and were also unsatisfactory in responsecharacteristics, etc., because of small spontaneous polarization. Also,even those compounds which show a high tendency of spontaneouspolarization had problem in stability as they possessed halogen atoms inthe molecular, and thus they could not be accepted as practical liquidcrystal compounds.

In view of the above, the present inventors have made studies fordeveloping a liquid crystal compound which can be widely applied tovarious types of display systems such as mentioned above, and as aresult they found out novel optically active benzene derivatives andachieved the present invention.

SUMMARY OF THE INVENTION

The present invention provides the optically active benzene derivativesrepresented by the above-described general formula (I). Such opticallyactive benzene derivatives have been unknown in the prior art anddisclosed for the first time by the present inventors. These novelcompounds can be produced, for instance, by reacting the optical activealcohol compounds represented by the formula (II): ##STR3## (wherein X,A, l, m, n and * represent the same as defined above) with aliphaticcarboxylic acids or acid anhydrides or acid halides thereof (these beinghereinafter referred to generically as aliphatic carboxylic acids)represented by the formula (III):

    R--COOH                                                    (III)

(wherein R is as defined above).

DETAILED DESCRIPTION OF THE INVENTION

The optical active alcohol compounds (II) used as starting material inthe above reaction can be obtained by subjecting dl-esters of theformula (IV): ##STR4## (wherein A, X, l, m and n are as defined above,and R' represents a lower alkyl group) to asymmetric hydrolysis by usingan esterase which has the ability to hydrolyze only one of theenantiomers of said esters.

The dl-esters (IV) used in the above reaction can be obtained byacylating the dl-alcohols represented by the formula (V): ##STR5##(wherein A, X, l, m and n are as defined above) by reacting them withlower alkylcarboxylic acids. The dl-alcohols (V) can be obtained byreducing the ketones represented by the formula (VI): ##STR6## (whereinA, X, l, m and n are as defined above) by using a reducing agent.

The ketones (VI) can be easily prepared from the reactions such as shownbelow by chemical formulae, the proper reaction being selected accordingto the type of substituent X:

i) In case X is --COO-- or --OCO--:

Said ketones are produced by the commonly used esterification reactions.##STR7##

ii) In case X is --CH₂ O-- or --OCH₂, or n=0:

Said ketones are produced by utilizing the commonly used etherificationor acylation reactions. ##STR8##

The reducing reactions for obtaining the dl-alcohols (V) from saidketones are carried out by using a reducing agent which is capable ofreducing ketones into alcohols.

As the reducing agent, in case the substituent X in the starting ketones(VI) is --COO-- or --OCO--, there are preferably used sodium boronhydride, lithium-tri-t-butoxyaluminum hydride, lithium-tri-s-butylboronhydride, borane and the like. In case the substituent X is --CH₂ O-- or--OCH₂ -- or n=0, sodium boron hydride, lithium boron hydride, zincboron hydride, lithium aluminum hydride, aluminum isopropoxide,lithium-t-butoxyaluminum hydride, lithium-tri-s-butylboron hydride,borane, alkali metal-ammonia and the like are preferably used.

Such reducing agent needs to be used in an amount of at least oneequivalent, usually 1 to 10 equivalents, to the starting ketone (VI).

The reducing reaction is usually carried out in a solvent. As thesolvent, there can be used those which are inert to the reaction, forexample, ethers such as tetrahydrofuran, dioxane, ethyl ether, etc.;alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol,etc.; aromatic hydrocarbons such as benzene, toluene, etc.; halogenatedhydrocarbons such as chloroform, dichloromethane, etc.; and the like.These solvents may be used either singly or in a suitable combination.

The reaction temperature may be selected from the range from -30° C. to100° C., but the range from -20° C. to 90° C. is preferred.

The dl-alcohols (V) can be obtained in a high yield from said reactionmixtures by subjecting them to such treatments as separation,concentration, distillation and crystallization. For producing thedl-esters (IV), it is not necessary to isolate the dl-alcohols (V) butthe reaction mixture may be immediately subjected to the next step.

The reaction for producing dl-esters (IV) from dl-alcohols (V) comprisesreacting dl-alcohols (V) with lower alkylcarboxylic acid derivatives toacylate said alcohols.

As the lower alkylcarboxylic acid derivatives used as acylating agent insaid acylation reaction, there are usually used acid anhydrides or acidhalides of lower alkylcarboxylic acids, such as acetic anhydride,propionic anhydride, acetic acid chloride or bromide, propionic acidchloride or bromide, butyryl chloride or bromide, valeroyl chloride orbromide, and the like.

The reaction of dl-alcohols (V) and a lower alkylcarboxylic acidderivative is carried out under the ordinary esterification reactionconditions by using a catalyst in the presence or absence of a solvent.

In case of using a solvent in this reaction, such solvent should be theone which is inert to the reaction, for example, aliphatic or aromatichydrocarbons, ethers, halogenated hydrocarbons and non-protonic polarsolvents, such as tetrahydrofuran, ethyl ether, acetone, methyl ethylketone, toluene, benzene, chlorobenzene, dichloromethane,dichloroethane, chloroform, carbon tetrachloride, dimethylformamide,hexane, etc. These solvents may be used either singly or in admixture.The amount of the solvent(s) to be used in the reaction is notspecified.

The amount of the lower alkylcarboxylic acid derivatives used in thereaction should be not less than one equivalent to the starting materialdl-alcohol (V). Its upper shreshold amount is not defined, but it ispreferably four equivalents to dl-alcohol (V).

As the catalyst, there can be used organic or inorganic basic materialssuch as dimethylaminopyridine, triethylamine, tri-n-butylamine,pyridine, picoline, imidazole, sodium carbonate, sodium methylate,potassium hydrogencarbonate and the like. The amount of the catalystused in the reaction, though not specified in this invention, is usually1 to 5 equivalents to dl-alcohol (V).

When an organic amine is used as solvent, such amine may act as acatalyst as well.

Acids such as toluenesulfonic acid, methanesulfonic acid, sulfuric acid,etc., may be used as catalyst.

The amount of the catalyst to be used can not be specified as it variesdepending on the type of the lower alkylcarboxylic acid derivatives,combination thereof with the catalyst used and other factors, but incase of using an acid halide as the lower alkylcarboxylic acidderivatives, the catalyst is used in an amount of one equivalent or moreto such acid halide.

The reaction temperature is usually in the range from -30° C. to 100°C., preferably -20° C. to 90° C.

The reaction time is not defined. The moment at which the startingmaterial dl-alcohol (V) has vanished may be taken as the end point ofthe reaction.

The reaction is followed by the ordinary separating operations such asextraction, separation of liquid phase, concentration,recrystallization, etc., by which dl-esters (IV) can be obtained in ahigh yield. If necessary, the resulting product may be purified bycolumn chromatography or other means, but the reaction mixture may besubjected in the form as it is to the treatment of the next step.

The reaction for obtaining optical active alcohols (II) from saiddl-esters (IV) comprises hydrolyzing one of the optical active compoundsof said dl-esters (IV) by using an esterase having the ability tohydrolyze only one of the enantiomers of said esters.

When the term "esterase" is used in this invention, it means esterasesof the broad sense including lipase.

As the microorganism producing the esterase used in the above reaction,there can be employed any of those microorganisms which are capable ofproducing an esterase having the ability to effectuate asymmetrichydrolysis of dl-esters (IV).

Examples of such esterase-producing microorganisms are those belongingto the genera Enterobacter, Arthrobacter, Brevibacterium, Pseudomonas,Alcaligenes, Micrococcus, Chromobacterium, Microbacterium,Corynebacterium, Bacillus, Lactobacillus, Trichoderma, Candida,Saccharomyces, Rhodotorula, Cryptocccus, Torulopsis, Pichia,Penicillium, Aspergillus, Rhizopus, Mucor, Aureobasidium, Actinomucor,Nocardia, Streptomyces, Hansenula and Achromobacter.

Culture of these microorganisms is usually accomplished according to aconventional method. For example, when a liquid culture is carried out,a culture medium can be obtained in the following manner:

For instance, a sterilized liquid medium [a malt extract-yeast extractmedium (prepared by dissolving 5 g of peptone, 10 g of glucose, 3 g ofmalt extract and 3 g of yeast extract in 1 liter of water, with pHadjusted to 6.5) for culture of mold and yeast fungi or a sweetenedbouillon medium (prepared by dissolving 10 g of glucose, 5 g of peptone,5 g of meat extract and 3 g of NaCl in 1 liter of water, with pHadjusted to 7.2) for culture of bacterial] is inoculated withmicroorganisms and subjected to reciprocal shaking culture usually at20°-40° C. for 1-3 days. If necessary, solid culture may be employed.

Some of the esterases usable in the reaction of this invention arecommercially available. The following can be mentioned as examples ofsuch commercially available esterases: Lipase P (lipase derived from thePseudomonas, available from Amano Pharmaceutical Co., Ltd.), Lipase AP(lipase derived from the Aspergillus, available from AmanoPharmaceutical Co., Ltd.), Lipase M-AP (lipase derived from the Mucor,available from Amano Pharmaceutical Co., Ltd.), Lipase MY (lipasederived from Candida Cylindlasse, available from Meito Sangyo Co.,Ltd.), Lipase PL (lipase derived from the Alcaligenes, available fromMeito Sangyo Co., Ltd.), Lipase AL (lipase derived from theAchromobacter, available from Metio Sangyo Co., Ltd.), Lipase Godo BSL(lipase derived from the Arthrobacter, available from Godo Shusei Co.,Ltd.), lipase derived from the Chromobacterium (available from ToyoBrewage Co., Ltd.), Talipase (lipase derived from the Rhizopus Delemar,available from Tanabe Pharmaceutical Co., Ltd.), and Lipase Saiken(lipace derived from the Rhizopus, available from Osaka BacterialResearch Institute).

It is also possible to use animal and plant esterases such as steapsin,pancreatin, swine liver esterase, wheat germ esterase, etc.

Enzymes obtained from animals, plants and microorganisms can be used asesterase in the reaction of this invention, and such enzymes can be usedin the various forms as desired, such as purified enzyme, crude enzyme,enzyme-containing substance, liquid culture of microorganism, culture,bacterial body, culture filtrate and their treated products.Combinations of enzymes and microorganisms are also usable. Further,fixed enzymes or fixed bacterial bodies, in which the enzymes orbacterial bodies have been fixed to a resin, etc., can be used.

The asymmetric hydrolysis reaction is carried out by vigorously stirringa mixture of the starting material dl-ester (IV) and said enzyme ormicroorganism usually in a buffer solution.

The buffer solution used in this reaction may be a commonly used buffersolution of an inorganic acid salt such as sodium phosphate, potassiumphosphate, etc., or an organic acid salt such as sodium acetate, sodiumcitrate, etc. The pH of the buffer solution is preferably 8 to 11 in thecase of cultures of alkaliphilic bacteria or alkaline esterases and 5 to8 in the case of cultures of non-alkaliphilic microorganisms oresterases having no alkali resistance. The concentration of the buffersolution is usually in the range of 0.05 to 2M, preferably 0.05 to 0.5M.

The reaction temperature is usually 10° to 60° C. and the reaction timeis generally 3 to 70 hours, though they are not defined in these ranges.

In case of using lipase belonging to the Pseudomonas or Arthrobacter insaid asymmetric hydrolysis reaction, there can be obtained an opticalactive alcohol compound (II) with a relatively high optical purity.

In this hydrolysis reaction, it is also possible to use an organicsolvent inert to the reaction, such as tolune, chloroform, methylisobutyl ketone, dichloromethane, etc., in addition to the buffersolution. Use of such organic solvent allows advantageous proceeding ofthe asymmetric hydrolysis.

As a result of such asymmetric hydrolysis reaction, only one of theoptical active substances of the starting material dl-ester (IV) ishydrolyzed to produce an optical active alcohol compound of the formula(II). On the other hand, the other optical active substance of saidstarting material dl-ester (IV), i.e. the optical active ester is leftunhydrolyzed.

After such hydrolysis reaction has been completed, the optical activealcohol compound (II) which is the hydrolyzate and the non-hydrolyzedoptical active substance of said starting ester (IV), or optical activeester, are separated by extracting the reaction solution with a solventsuch as methyl isobutyl ketone, ethyl acetate, ethyl ether, etc.,distilling off the solvent from the organic layer and subjecting theconcentrated residue to column chromatography, or by other methods.

The optical active ester obtained here may if necessary be furtherhydrolyzed to be turned into an optical active alcohol compound (II)which is an enantiomer of the previously obtained optical active alcoholcompound (II).

For obtaining the objective optically active benzene derivative fromsuch optical active alcohol compound (II), said compound (II) is reactedwith an aliphatic carboxylic acid.

The aliphatic carboxylic acids usable in this reaction include thoselisted below as well as their acid anhydrides or acid halides (such asacid chloride and acid bromide): acetic acid, propionic acid, butanoicacid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid,nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid,tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoicacid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid,eicosanic acid, isobutyric acid, 2-methylbutanoic acid,4-methylpentanoic acid, 2-methylhexanoic acid, 2-methylheptanoic acid,2-methyloctanoic acid, 2-methylbutanoic acid, 2,3-dimethylbutanoic acid,2,3,3-trimethylbutanoic acid, 2-methylpentanoic acid, 3-methylpentanoicacid, 2,3-dimethylpentanoic acid, 2,4-dimethylpentanoic acid,2,3,3,4-tetramethylpentanoic acid, 2-methylhexanoic acid,3-methylhexanoic acid, 4-methylhexanoic acid, 2,5-dimethylhexanoic acid,2-methylheptanoic acid, and 2-methyloctanoic acid. Among the abovealiphatic carboxylic acids, those having an asymmetric carbon atom maybe used even if they are either racemic or optical active compound.

Certain of these optical active carboxylic acids can be obtained byoxidizing the corresponding alcohols or by the reductive deamination ofthe amino acids. Some optical active aliphatic carboxylic acids exist innature. Also, some of them can be derived from the optical active aminoacids or optical active oxyacids such as listed below which existnaturally or are obtainable by resolution: alanine, valine, leucine,isoleucine, phenylalanine, serine, threonine, allothreonine, homoserine,alloisoleucine, tertleucine, 2-aminobutyric acid, norvaline, norleucine,ornithine, lysine, hydroxylysine, phenylglysine, trifluoroalanine,aspartic acid, glutamic acid, lactic acid, mandelic acid, tropic acid,3-hydroxybutyric acid, malic acid, tartaric acid, and iso-propylmalicacid.

The reaction of optical active alcohol compound (II) and aliphaticcarboxylic acid is usually carried out in the presence or absence of asolvent and generally in the presence of a catalyst.

The solvents usable in this reaction are the ones which are inert to thereaction, for example, aliphatic or aromatic hydrocarbons, esters,ethers and halogenated hydrocarbons such as tetrahydrofuran, ethylether, acetone, methyl ethyl ketone, ethyl acetate, toluene, benzene,chlorobenzene, dichloromethane, dichloroethane, chloroform, carbontetrachloride, dimethylformamide and hexane, which may be used eithersingly or in combination. The amount of such solvent to be used in saidreaction is not specifically defined.

The amount of acid anhydride or acid halide of aliphatic carboxylic acidto be used in the reaction should be not less than one equivalent to theoptical active alcohol compound. Its upper threshold amount is notsubject to any definite limitation, but it is preferably 4 equivalentsto said alcohol compound.

As the catalyst, organic or inorganic basic materials such asdimethylaminopyridine, triethylamine, tri-n-butylamine, pyridine,picoline, imidazole, sodium carbonate, sodium methylate and potassiumhydrogen-carbonate can be used. Organic or inorganic acids such astoluenesulfonic acid, methanesulfonic acid, sulfuric acid, etc., arealso usable as catalyst.

In case of using, for instance, an acid halide of aliphatic carboxylicacid as starting material, pyridine is most preferably used as catalyst.

The amount of the catalyst to be used in the reaction varies accordingto the type of acid anhydride or acid halide of aliphatic carboxylicacid used, combination thereof with the catalyst used, etc., but in caseof using an acid halide, the catalyst should be used in an amount of atleast one equivalent to the acid halide.

In case of using an aliphatic carboxylic acid, dehydrating-condensationis carried out by using 1 to 4 equivalents, preferably 1 to 2equivalents of said carboxylic acid to one equivalent of the opticalactive alcohol compound used as starting material. As condensingreagent, there can be used carbodiimides such asN,N'-dicyclohexylcarbodiimide,N-cyclohexyl-N'-(4-diethylamino)cyclohexyl carbodiimide, etc., and ifnecessary an organic base such as 4-pyrrolidinopyridine, pyridine,triethylamine, etc. The amount of such condensing agent to be used inthe reaction should be 1 to 1.2 equivalent to said carboxylic acid, andthe amount of the base to be used should be 0.01 to 0.2 equivalent tosaid condensing agent.

As the solvent, those inert to the reaction such as mentioned previouslycan be used.

The reaction temperature is usuallly -30° C. to 100° C., preferably -25°C. to 80° C.

No particular limit is imposed on the reaction time. The moment at whichthe optical active alcohol compound used as starting material hasvanished may be supposed to be the end point of the reaction.

After the end of the reaction, the desired optically active benzenederivative of the formula (I) can be isolated from the reaction mixtureby subjecting to the ordinary separating operations such as filtration,extraction, separation of liquid phase, concentration, etc. If necessarythe isolated substance may be purified by column chromatography or othermeans.

The optically active benzene derivatives obtainable from theabove-described process include, for instance,p-(1-alkylcarbonyloxyethyl)phenyl benzoate,p'-(1-alkylcarbonyloxyethyl)phenyl p-halobenzoate,p'-(1-alkylcarbonyloxyethyl)phenyl p-alkylbenzoate,p'-(1-alkylcarbonyloxyethyl)phenyl p-alkyloxybenzoate,4'-(1-alkylcarbonyloxy ethyl)-4-biphenylyl benzoate,4'-(1-alkylcarbonyloxyethyl)-4-biphenylyl p-halobenzoate,4'-(1-alkylcarbonyloxyethyl)-4-biphenylyl p-alkylbenzoate,4'-(1-alkylcarbonyloxyethyl)-4-biphenylyl p-alkyloxybenzoatep-(1-alkylcarbonyloxyethyl)phenyl 4-biphenylcarboxylate,p-(1-alkylcarbonyloxyethyl)phenyl 4'-halo-4-biphenylcarboxylate,p-(1-alkylcarbonyloxyethyl)phenyl 4-alkyl-4-biphenylcarboxylate,p-(1-alkylcarbonyloxyethyl)phenyl 4'-alkyloxy-4-biphenylcarboxylate,4'-(1-alkylcarbonyloxyethyl)-4-biphenyl 4-biphenylcarboxylate,4'-(1-alkylcarbonyloxyethyl)-4-biphenyl 4'-halo-4-biphenylcarboxylate,4'-(1-alkylcarbonyloxyethyl)-4-biphenyl 4'-alkyl-4-biphenylcarboxylate,and 4'-(1-carbonyloxyethyl)-4-biphenyl4'-alkyloxy-4-biphenylcarboxylate.

In the above-shown examples of the optical active compounds according tothis invention, "alkyl" represents alkyl groups having 1 to 20 carbonatoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl,hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, isopropyl,1-methylpropyl, 3-methylbutyl, 1-methylpentyl, 1-methylhexyl and1-methylheptyl. Such "alkyl" may also represent optical active alkylgroups such as 1-methylpropyl, 1,2-dimethylpropyl,1,2,2-trimethylpropyl, 1-methylbutyl, 1,3-dimethylbutyl,1,2,2,3-tetramethylbutyl, 1-methylpentyl, 2-methylpentyl,3-methylpentyl, 1,3-dimethylpentyl, 1-methylhexyl, and 1-methylheptyl.

Shown above are the optically active benzene derivatives in which thebonding groups X is --COO--, but those in which the bonding group is--OCO--, --CH₂ O-- or --OCH₂ -- instead of --COO-- or n=0 can be alsosimilarly obtained from the process of this invention.

The optically active benzene derivatives provided according to thisinvention can be utilized as a liquid-crystalline substance, and many ofsuch derivatives present a liquid crystal phase which is either S_(A)phase or S_(C) * phase.

Generally, in the liquid crystals having S_(C) * phase, especiallyferroelectric liquid crystals, the molecules are arranged with aninclination to a specific direction and the direction of inclinationshifts slightly from layer to layer to form a spiral structure in themolecular orientation (Mol. Cryst. and Liq. Cryst., 40, 30 (1977)). Itis said that spontaneous polarization tends to occur at a location whichis in a direction orthogonal to the axis of said spiral, and it ispointed out as the conditions for such ferroelectric liquid crystal thatthe crystal has an optical active group for inducing a spiral structureat the end of the molecule and that, in order to induce spontaneouspolarization, the crystal has at the end of the molecule a substituenthaving a permanent dipole in the direction substantially vertical to themajor axis of the molecule.

While the existence of an optical active group in the molecule isessential as said above, it has been considered desirable to bring theoptical active group close to the core for inducing even greaterspontaneous polarization (Liquid Crystals and Ordered Fluids, Vol. 4,1-32 (1982)). But on the other hand, it has been also considered thatwhen the optical active center comes close to the core, it becomesdifficult for the compound to assume a liquid crystal phase.

Among the conventional liquid crystal compounds, however, there has beennone having an asynmetric carbon atom at a position directly bonded tothe core.

The optically active benzene derivatives represented by the formula (I)according to this invention can satisfy said conditions and has a quitenovel molecular structure in which the optical active center is locatedat a position directly bonded to the core, and further it has beenclarified that such compounds are capable of having very greatspontaneous polarization.

In practical utilization of such liquid-crystalline materials, they cannot only be provided as a mixed composition but can be also added to aferroelectric liquid crystal having very small spontaneous polarizationto provide a composition capable of having large spontaneouspolarization.

In use of the compounds of the this invention, it is considered thatthose of the compounds of this invention which take the S_(C) * phase initself have higher utility, and especially those which take such phaseenantiotropically are preferred. In view of this, the compounds of theformula (I) wherein X is --OCO--, l=2 and n=1 are most favorable forpractical utilization.

Even those compounds which take no S_(C) * phase are also useful. Theymay be added to an S_(C) or S_(C) * phase liquid crystal having no orvery small spontaneous polarization to enlarge spontaneous polarizationof the liquid crystal composition to thereby increase response speed.The compounds of this invention prove advantageous in such mixing asthey have high compatibility and excellent stability.

Also, the compounds of the formula (I) wherein X is --CH₂ O, l is 1 andA is a hydrogen atom, a halogen atom, a lower alkyl or a lower alkoxylgroup are useful as an intermediate. For instance, when they aresubjected to catalytic hydrogenation, they are debenzylated to givebenzene alcohols. ##STR9##

Such benzene alcohols can be led into the compounds of this invention byreacting them with benzene carboxylic acids.

As described above, the optically active benzene derivatives of thisinvention are useful as a liquid-crystalline material. For instance,they can be effectively utilized as a material for liquid crystalelements, optical switching elements, etc. In such practicalapplications, the optically active benzene derivative of this inventionmay be used alone or in combination with other liquid crystal compoundaccording to the purpose of use and other factors involved. The methodsfor utilization are diversified.

Thus, the novel optical active benzene derivatives of this invention canbe effectively utilized as a novel liquid-crystalline substance and havean extremely high industrial utility value.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be further described below in accordance withthe examples thereof.

EXAMPLE 1 (MATERIAL PREPARATION)

90.45 g (0.4 mol) of 4-benzyloxyacetophenone, 300 ml of tetrahydrofuranand 100 ml of methanal were supplied into a four-necked flask equippedwith a stirrer and a thermometer. Then 15.14 g (0.4 mol) of sodiumborohydride was added at 15°-25° C. over a period of 2 hours. After keptat the same temperature for 5 hours, the mixture was poured intoice-water and extracted twice with 500 ml of ethyl acetate. The organiclayer was concentrated under reduced pressure to obtain 88.5 g of4-benzyloxy-1-phenethyl alcohol in a 97% yield.

68.44 g (0.3 mol) of 4-benzyloxy-1-phenethyl alcohol was dissolved in amixed solution of 300 ml of toluene and 50 ml of pyridine, and then25.91 g (0.33 mol) of acetyl chloride was added at 15°-20° C. over aperiod of 2 hours. The mixture was kept at the same temperature for onehour and then at 40°-50° C. for 2 hours.

The reaction mixture was cooled below 10° C. and added with 200 ml ofwater. After separating the liquid phase, the organic layer was washedwith 1N hydrochloric acid solution, water, 5% sodium carbonate and watersuccessively in that order, then concentrated under reduced pressure andpurified by column chromatography to give 79.8 g (98.5% yield) of aceticester of 4-benzyloxy-1-phenethyl alcohol.

67.5 g (0.25 mol) of this acetic ester of 4-benzyloxy-1-phenethylalcohol was mixed with 700 ml of 0.3M phosphate buffer solution (pH 7.5)and 6.75 g of Amano Lipase P and vigorously stirred at 40°-45° C. for 40hours. The reaction mixture was extracted with 500 ml of ethyl acetate.The organic layer was concentrated under reduced pressure and theresidue was purified by column chromatography using a 5:2 mixed solutionof toluene and ethyl acetate as developing solvent to give 23.38 g (41%yield) of (+)-4-benzyloxy-1-phenethyl alcohol ([α]_(D) ²⁰ =+35.9° (c=1,CHCl₃), m.p.=66°-68° C.).

EXAMPLE 2 (MATERIAL PREPARATION)

120.9 g (0.4 mol) of 4'-acetyl-4-benzyloxybiphenyl, 400 ml oftetrahydrofuran and 100 ml of methanol were supplied into a four-neckedflask equipped with a stirrer and a thermometer. Then 15.14 g (0.4 mol)of sodium borohydride was added at 15°-25° C. over a period of 2 hours.The mixture was kept at the same temperature for 5 hours, then pouredinto ice-water and extracted twice with 500 ml of chloroform. Theorganic layer was concentrated under reduced pressure to obtain 117.4 gof 4-benzyloxy-4'-(1-hydroxyethyl)biphenyl in a 96.5% yield.

91.25 g (0.3 mol) of this 4-benzyloxy-4'-(1-hydroxyethyl)biphenyl wasdissolved in a mixed solution of 400 ml of toluene and 100 ml ofpyridine, and then 25.91 g (0.33 mol) of acetyl chloride was added at15°-20° C. over a period of 2 hours. The mixture was kept at the sametemperature for one hour and then at 40°-50° C. for 2 hours.

The reaction mixture was cooled below 10° C. and added with 300 ml ofwater. After separating the liquid phase, the organic layer was washedwith 1N hydrochloric acid solution, water, 5% sodium carbonate and watersuccessively in that order, then concentrated under reduced pressure andpurified by column chromatography to give 101.57 g of acetic ester of4-benzyloxy-4'-(1-hydroxyethyl)biphenyl in a 97.8% yield.

86.55 g (0.25 mol) of this acetic ester of4-benzyloxy-4'-(1-hydroxyethyl)biphenyl was mixed with 2,000 ml of 0.3Mphosphate buffer solution (pH 7.5), 50 ml of chloroform and 50 g ofAmano Lipase P and stirred vigorously at 40°-45° C. for 120 hours. Thereaction mixture was extracted with 1,000 ml of chloroform. The organiclayer was concentrated under reduced pressure and the residue waspurified by column chromatography using a 5:2 mixed solution of tolueneand ethyl acetate to give 28.9 g of(+)-4-benzyloxy-4'-(1-hydroxyethyl)biphenyl ([α]_(D) ²⁰ =+34.8° (c=1,CHCl₃), m.p.=158°-159° C.).

EXAMPLES 3 AND 4 (MATERIAL PREPARATION)

The procedure of Material Preparation Example 1 was followed except thatthe ketones shown in Table 1 were used as starting material. The resultsare shown in Table 1.

                                      TABLE 1                                     __________________________________________________________________________                        Optical active alcohol produced*.sup.1                    Starting ketone     Yield                                                                             Melting                                                                             [α].sub.D.sup.20 c = 1,                   Example                                                                            A    X     l m %   point (°C.)                                                                  chloroform                                      __________________________________________________________________________    3    C.sub.8 H.sub.17 O                                                                 --CH.sub.2 O                                                                        1 2 44  158.5-160                                                                           +21°                                     4    "    --OCH.sub.2 --                                                                      2 1 46    143-144                                                                           +24°                                     __________________________________________________________________________     *.sup.1 Substituent A, X, l and m are the same as those of the ketones        used starting material.                                                  

EXAMPLE 5 (MATERIAL PREPARATION)

40.2 g (0.1 mol) of 4'-acetyl-4-biphenyl ester of 4-pentyloxybenzoicacid, 100 ml of ethanol and 100 ml of chloroform were supplied into afour-necked flask furnished with a stirrer and a thermometer. Then 1.9 g(0.05 mol) of sodium borohydride was added at 20°-30° C. over a periodof 10 minutes.

The mixture was kept at the same temperature for 3 hours, then pouredinto ice-water and extracted twice with 200 ml of chloroform.

The organic layer was washed with water and concentrated under reducedpressure to obtain 40.1 g of 4'-(1-hydroxyethyl)-4-biphenyl ester of4-pentyloxybenzoic acid in a 99.1% yield.

20.2 g (0.05 mol) of said 4-pentyloxybenzoic ester was dissolved in amixed solvent of 100 ml of pyridine and 200 ml of chloroform, and then5.5 g (0.07 mol) of acetyl chloride was added at 10°-15° C. over aperiod of one hour. The mixture was kept at 40°-50° C. for 2 hours.

The resulting reaction mixture was cooled below 10° C. and added with200 ml of water. After separating the liquid phase, the organic layerwas washed with 3N hydrochloric acid, water, 7% sodium hydrogencarbonateand water successively in that order and concentrated under reducedpressure to obtain 21.6 g of 4'-(1-acetoxyethyl)-4-biphenylyl ester of4-pentyloxybenoic acid in a 97% yield.

8.9 g (0.02 mol) of said ester of 4-pentyloxybenzoic acid was mixed with300 ml of 0.3M phosphate buffer solution (pH 7), 20 ml of chloroform and1.8 g of Amano Lipase P and stirred vigorously at 35°-40° C. for 24hours.

The reaction mixture was extracted with 300 ml of chloroform. Theorganic layer was concentrated under reduced pressure and the residuewas purified by column chromatography using a 20:1 mixed solution ofchloroform and ethyl acetate as developing solvent to give 3.6 g of(+)-4'-(1-hydroxyethyl)-4-biphenylyl ester of 4-pentyloxybenzoic acid(melting point: 186°-188° C., [α]_(D) ²⁰ =+24.2° (c=1, chloroform).

EXAMPLES 6-12 (MATERIAL PREPARATION)

The procedure of Material Preparation Example 5 was followed except thatthe ketones shown in Table 2 were used as starting material. Theobtained results are shown in Table 2.

                                      TABLE 2                                     __________________________________________________________________________                         Optical active alcohol produced*.sup.1                   Starting ketone      Yield                                                                             Melting                                                                             [α].sub.D.sup.20 c = 1,                  Example                                                                            A     X     l m %   point (°C.)                                                                  chloroform                                     __________________________________________________________________________    6    C.sub.8 H.sub.17 O                                                                  --COO--                                                                             1 2 45  135-136                                                                             +22°                                    7    C.sub.10 H.sub.21 O                                                                 --COO--                                                                             1 2 46  138.5-140                                                                           +20.4°                                  8    C.sub.8 H.sub.17 O                                                                  --COO--                                                                             1 1 49  85-86 +22.3°                                  9    C.sub.8 H.sub.17 O                                                                  --OCO--                                                                             1 1 45  134-135                                                                             +29.1°                                  10   C.sub.5 H.sub.11                                                                    --COO--                                                                             1 2 46  142-143                                                                             +26.4°                                  11   C.sub.8 H.sub.17                                                                    --COO--                                                                             1 2 46  110.5-111                                                                           +24.1°                                  12   C.sub.8 H.sub.17 O                                                                  --COO--                                                                             2 1 45  149-150                                                                             +18.3°                                  __________________________________________________________________________     *.sup.1 Substituent A, X, l and m are the same as those of the ketones        used as a starting material.                                             

EXAMPLE 13 (MATERIAL PREPARATION)

500 ml of ethanol, 23.96 g (0.106 mol) of 4-acetyl-4'-methoxybiphenyland 5.60 g (0.148 mol) of sodium borohydride were applied into athree-necked flask and stirred under heating at 50° C. for about 2hours. After the reaction was completed, ethanol was distilled off underreduced pressure and the residue was extracted with diethyl ether. Theether layer was washed well with water and dried over anhydrousmagnesium sulfate. The solvent was then distilled off to give a whitesolid.

This white solid was dissolved in 200 ml of dry dichloromethane,followed by addition of 50 ml of pyridine. Then a solution of 12.5 g(0.159 mol) of acetyl chloride in 50 ml of dichloromethane was addeddropwise. About 2 hours later, the reaction solution was added into 300ml of 3N hydrochloric acid and extracted. The organic layer was washedwith water and a 7% sodium hydrogencarbonate solution successively inthat order and dried over anhydrous magnesium sulfate. Then the solventwas distilled off. The resulting white solid was recrystallized fromethanol to give 20.36 g of di-4-(1-acetoxyethyl)-4'-methoxybiphenyl in a71% yield.

A 10 ml chloroform solution of 6.0 g (0.022 mol) ofdi-4-(1-acetoxyethyl)-4'-methoxybiphenyl and 1.0 g of lipase ("Amano P"lipase made by Amono Pharmaceutical Co., Ltd.) were added into 300 ml ofa 0.1M phosphate buffer solution (pH 7) and stirred vigorously under anitrogen atmosphere at 35° C. for 29 hours for reacting said materials.

The resulting reaction solution was extracted with ethyl acetate. Theextract was concentrated and purified by column chromatography using achloroform-ethyl acetate mixture as developing solvent to give 1.9 g(43% yield) of (+)-4-(1-hydroxyethyl)-4'-methoxybiphenyl ([α]_(D) ²⁵=+40.1° (c=1, chloroform), melting point: 132°-133° C.).

EXAMPLE 14 (MATERIAL PREPARATION)

The procedure of Material Preparation Example 13 was followed exceptthat 4-acetyl-4'-octyloxybiphenyl was used as starting material toobtain (+)-4-(1-hydroxyethyl)-4'-octyloxybiphenyl ([α]_(D) ²⁵ =+28.6°(c=1, chloroform), melting point: 124°-125° C.).

EXAMPLE 15

4.56 g (20 mmol) of (+)-4-benzyloxy-1-phenethyl alcohol was dissolved in50 ml of dry pyridine, and to this solution was added dropwise 1.73 g(22 mmol) of acetyl chloride. The mixture was stirred at roomtemperature for one hour, then poured into 400 ml of 2N hydrochloricacid and extracted with 200 ml of toluene. The toluene layer was washedwith water, a 7% sodium bicarbonate solution and water successively inthat order and then dried over anhydrous magnesium sulfate. The solventwas distilled off under reduced pressure from this toluene solution, andthe resulting white solid was purified by column chromatography packedwith 200 g of silica gel to obtain 5.35 g of acetic acid ester of(+)-4-benzyloxy-1-phenethyl alcohol in a 99% yield. It was furtherrecrystallized from ethanol. [α]_(D) ²⁵ =+93° (c=1, CHCl₃ ; meltingpoint: 52°-53° C.

EXAMPLE 16

The procedure of Example 15 was repeated but by using propionic acidchloride in place of acetyl chloride to obtain propionic acid ester of(+)-4-benzyloxy-1-phenethyl alcohol. [α]_(D) ²⁵ =+89° (c=1, CHCl₃);melting point: 48° C.

EXAMPLE 17

The procedure of Example 15 was followed except that(+)-4-(4-methylbenzyl)oxy-1-phenethyl alcohol was used in place of(+)-4-benzyloxy-1-phenethyl alcohol to obtain acetic acid ester of(+)-4-(4-methylbenzyl)oxy-1-phenethyl alcohol. [α]_(D) ²⁵ =+91° (c=1,CHCl₃); melting point: 54°-55° C.

EXAMPLE 18

In Example 15, (+)-4-benzyloxy-1-phenethyl alcohol was replaced by(+)-4-(4-methoxybenzyl)oxy-1-phenethyl alcohol and acetyl chloride wasreplaced by decanoyl chloride, and otherwise the same procedure as

Example 15 was followed to obtain decanoic acid ester of(+)-p-(4-methoxybenzyl)oxy-1-phenethyl alcohol.

EXAMPLE 19

6.09 g (20 mmol) of (+)-4-benzyloxy-4'-(1-hydroxyethyl)biphenyl wasdissolved in 100 ml of dry pyridine, followed by dropwise addition of1.73 g (22 mmol) of acetyl chloride. The mixture was stirred at roomtemperature for one hour, then poured into 1 liter of 2N hydrochloricacid and extracted with 300 ml of toluene. The toluene layer was washedwith water, then with a 7% sodium bicarbonate solution and again withwater successively in that order and then dried over anhydrous magnesiumsulfate. This toluene solution was distilled under reduced pressure toremove the solvent and the residual white solid was purified by columnchromatography packed with 200 g of silica gel to obtain 6.86 g of(+)-4-benzyloxy-4'-(1-acetoxyethyl)biphenyl in a 99% yield. It wasfurther purified by recrystallization from ethanol. [α]_(D) ²⁵ =+56.3°(c=1, CHCl₃); melting point: 137° C.

EXAMPLE 20

The procedure of Example 19 was followed except for use of propionicacid chloride in place of acetyl chloride to obtain(+)-4-benzyloxy-4'-(1-propionyloxyethyl)biphenyl. [α]_(D) ²⁵ =+55° (c=1,CHCl₃); melting point: 125° C.

EXAMPLE 21

By using (+)-4-(p-chlorobenzyl)oxy-4'-(1-hydroxyethyl)biphenyl insteadof (+)-4-benzyloxy-4'-(1-hydroxyethyl)biphenyl, the procedure of Example19 was followed to obtain acetic acid ester of(+)-4-(p-chlorobenzyl)oxy-4'-(1-hydroxyethyl)biphenyl. [α]_(D) ²⁵ =+52°(c=1, CHCl₃); melting point: 140°-141° C.

EXAMPLE 22

4.47 g (10 mmol) of (+)-4'-(1-hydroxyethyl)-4-biphenyl ester of4-octyloxybenzoic acid was dissolved in 100 ml of dry pyridine, and then2.7 g (15 mmol) of octanoyl chloride was added dropwise. The mixture wasstirred at room temperature for one hour, poured into 1 liter of 2Nhydrochloric acid and extracted with 500 ml of toluene. The toluenelayer was washed with water, a 7% sodium bicarbonate solution and watersuccessively in that order and then dried over anhydrous magnesiumsulfate. This toluene solution was distilled under reduced pressure toremove the solvent and the residual white solid was purified by columnchromatography packed with 400 g of silica gel to give 5.58 g (95%yield) of (+)-4'-(1-heptylcarbonyloxyethyl)-4-biphenylyl ester of4-octyloxybenzoic acid. This was further purified by recrystallizationfrom ethanol. [α]_(D) ²⁵ =49.4° (c=1, chloroform); phase transitiontemperature (°C.): ##STR10##

EXAMPLE 23

The procedure of Example 22 was followed except that(+)-4-(1-hydroxyethyl)phenyl ester of 4-octyloxybenzoic acid was used inplace of (+)-4'-(1-hydroxyethyl)-4-biphenyl ester of 4-octyloxybenzoicacid and that hexanoyl chloride was used in place of octanoyl chlorideto obtain (+)-4-(1-pentylcarbonyloxyethyl)phenyl ester of4-octyloxybenzoic acid. [α]_(D) ²⁵ =+51° (c=1, CHCl₃); melting point:5°-7° C.

EXAMPLE 24

The procedure of Example 23 was repeated but by using acetyl chloride inplace of hexanoyl chloride to obtain(+)-4-(1-methylcarbonyloxyethyl)phenyl ester of 4-octyloxybenzoate.[α]_(D) ²⁵ =+60° (c=1, CHCl₃): melting point: 46°-47° C.

EXAMPLES 25-62

According to the process of Example 15 or 22, there were produced theoptically active benzene derivatives shown in Table 3. The opticalrotation and phase transition temperature of the obtained compounds areshown in Table 3.

                                      TABLE 3                                     __________________________________________________________________________     ##STR11##                                                                                                [α].sub.D.sup.25                            Example                                                                            A     X     l m R      (c = 1, CHCl.sub.3)                                                                   Phase transition temperature                                                  (°C.)                              __________________________________________________________________________    25   C.sub.5 H.sub.11 O                                                                  COO   1 2 CH.sub.3                                                                             +70°                                                                            ##STR12##                                26   "     "     " " C.sub.5 H.sub.11                                                                     +58°                                       27   "     "     " " C.sub.8 H.sub.17                                                                     +54°                                                                            ##STR13##                                28   "     "     " " C.sub.17 H.sub.35                                                                    +43°                                                                            ##STR14##                                29   C.sub.8 H.sub.17 O                                                                  "     " " CH.sub.3                                                                             +57°                                                                            ##STR15##                                30   "     "     " " C.sub.3 H.sub.7                                                                      +61°                                                                            ##STR16##                                31   "     "     " " C.sub.5 H.sub.11                                                                     +56°                                                                            ##STR17##                                32   C.sub.8 H.sub.17 O                                                                  COO   1 2 C.sub.9 H.sub.19                                                                     +52°                                                                            ##STR18##                                33   C.sub.10 H.sub.21 O                                                                 "     " " CH.sub.3                                                                             +60°                                                                            ##STR19##                                34   "     "     " " C.sub.3 H.sub.7                                                                      +58°                                                                            ##STR20##                                35   "     "     " " C.sub.5 H.sub.11                                                                     +52°                                                                            ##STR21##                                36   "     "     " " C.sub.8 H.sub.17                                                                     +48°                                                                            ##STR22##                                37   C.sub.16 H.sub.33 O                                                                 "     " " CH.sub.3                                                                             +45°                                                                            ##STR23##                                38   C.sub.5 H.sub.11                                                                    COO   1 2 C.sub.8 H.sub.17                                                                     +56°                                                                            ##STR24##                                39   C.sub.8 H.sub.17                                                                    "     " " C.sub.5 H.sub.11                                                                     +54°                                                                            ##STR25##                                40   C.sub.8 H.sub.17 O                                                                  "     2 1 CH.sub.3                                                                             +45°                                                                            ##STR26##                                41   "     "     " " C.sub.5 H.sub.11                                                                     +44°                                                                            ##STR27##                                42   "     "     " " C.sub.9 H.sub.19                                                                     +39°                                                                            ##STR28##                                43   "     "     " " C.sub.17 H.sub.35                                                                    +27°                                                                            ##STR29##                                44   "     OCO   1 1 C.sub.5 H.sub.11                                                                     +56°                                       45   C.sub.10 H.sub.21 O                                                                 OCO   1 1 C.sub.9 H.sub.19                                                                     +46°                                       46   C.sub.8 H.sub.17 O                                                                  "     " 2 C.sub.5 H.sub.11                                                                     +55°                                                                            ##STR30##                                47   C.sub.10 H.sub.21 O                                                                 "     " " C.sub.3 H.sub.7                                                                      +54°                                                                            ##STR31##                                48   "     "     " " C.sub.5 H.sub.11                                                                     +53°                                                                            ##STR32##                                49   "     "     " "                                                                                ##STR33##                                                                           +40°                                                                            ##STR34##                                50   C.sub.16 H.sub.33 O                                                                 "     " " C.sub.5 H.sub.11                                                                     +42°                                                                            ##STR35##                                51   C.sub.8 H.sub.17 O                                                                  OCO   2 1 C.sub.3 H.sub.7                                                                      +60°                                                                            ##STR36##                                52   "     "     " " C.sub.5 H.sub.11                                                                     +57°                                                                            ##STR37##                                53   "     "     " " C.sub.9 H.sub.19                                                                     +50°                                                                            ##STR38##                                54   "     "     " " C.sub.17 H.sub.35                                                                    +40°                                                                            ##STR39##                                55   "     "     " "                                                                                ##STR40##                                                                           +41°                                                                            ##STR41##                                56   C.sub.10 H.sub.21 O                                                                 "     " " C.sub.3 H.sub.7                                                                      +53°                                                                            ##STR42##                                57   C.sub.10 H.sub.21 O                                                                 OCO   2 1                                                                                ##STR43##                                                                           +40°                                                                            ##STR44##                                58   C.sub.12 H.sub.25 O                                                                 "     " " C.sub.3 H.sub.7                                                                      +51°                                                                            ##STR45##                                59   C.sub.6 H.sub.13 O                                                                  "     " " C.sub.5 H.sub.11                                                                     +58°                                       60   C.sub.7 H.sub.15                                                                    "     " " "      +55°                                       61   C.sub.10 H.sub.21                                                                   "     " " C.sub.3 H.sub.7                                                                      +53°                                                                            ##STR46##                                62   C.sub.12 H.sub.25                                                                   "     " " "      +50°                                       __________________________________________________________________________     S.sub.1 indicates unidentified smectic phase.                                 S.sub.x * indicates unidentified ferroelectronic smectic phase.               S.sub.x indicates unidentified smectic phase.                            

EXAMPLE 63

2.0 g (4.6 mmol) of(+)-4-(p-octyloxy)-benzyloxy-4'-(1-hydroxyethyl)biphenyl was dissolvedin 20 ml of pyridine, followed by addition of 0.9 g (5.5 mmol) ofoctanoyl chloride. The mixture was stirred at 40°-45° C. for one hour,then poured into 400 ml of 3N hydrochloric acid and extracted with 300ml of toluene. The toluene layer was washed with water, then with a 7%sodium bicarbonate solution and again with water and then dried overanhydrous magnesium sulfate. The solvent was distilled off under reducedpressure from the organic layer and the resulting light-yellow solid waspurified by silica gel column chromatography to obtain 2.4 g (96% yield)of (+)-4-(p-octyloxy)benzyloxy-4'-(1-octanoyloxyethyl)biphenyl. [α]_(D)²⁵ =+47° (c=1, CHCl₃).

EXAMPLES 64-67 and 76 and 77

By following the process of Example 63, there were produced the opticalactive benzene derivatives shown in Table 4.

The property values of the obtained compounds are shown in Table 4.

                  TABLE 4                                                         ______________________________________                                                                [α].sub.D.sup.25 (c = 1,                        Example                                                                              A        X         l   m   R     CHCl.sub.3)                           ______________________________________                                        64     C.sub.16 H.sub.33 O                                                                    --CH.sub.2 O--                                                                          1   2   C.sub.7 H.sub.15                                                                    +36°                           65     C.sub.8 H.sub.17 O                                                                     --OCH.sub.2 --                                                                          1   2   C.sub.5 H.sub.11                                                                    +53°                           66     C.sub.10 H.sub.21 O                                                                    "         2   1   C.sub.3 H.sub.7                                                                     +56°                           67     C.sub.10 H.sub.21                                                                      "         "   "    "    +50°                           76     C.sub.8 H.sub.17 O                                                                     --CH.sub.2 O--                                                                          1   2   CH.sub.3                                                                            +68°                           77      "       "         1   2   C.sub.5 H.sub.11                                                                    +58°                           ______________________________________                                    

EXAMPLE 68

2.75 g (12 mmol) of (+)-4-(1-hydroxyethyl)-4'-methoxybiphenyl wasdissolved in a mixed solution of 100 ml of toluene and 20 ml of pyridinein four-necked flask provided with a stirrer and a thermometer. Then3.52 g (20 mmol) of nonanoyl chloride was added to the solution at15°-20° C.

The mixed solution was kept at the same temperature for one hour andthen at 40°-50° C. for 2 hours.

The reaction mixture was cooled below 10° C. and added with 200 ml ofwater. After separating the liquid phase, the organic layer was washedwith a 2N hydrochloric acid solution, water, a 5% sodium bicarbonatesolution and water in that order successively.

The organic layer was concentrated under reduced pressure and purifiedby column chromatography to obtain 4.3 g (97% yield) of(+)-4-(1-nonanoyloxyethyl)-4'-methoxybiphenyl. [α]_(D) ²⁵ =+73° (c=1,chloroform); melting point: 59°-60° C.

EXAMPLES 69 AND 70

The procedure of Example 68 was followed except for use of the reactantsshown in Table 5.

The results are shown in Table 5.

EXAMPLE 71

38.5 g of 4"-acetyl-4-octylterphenyl, 500 ml of ethanol and 5.67 g ofsodium boron hydride were supplied into a four-necked flask and stirredat 50° C. for 2 hours.

After the reaction was complete, ethanol was distilled off under reducedpressure and the residue was extracted with toluene. The organic layerwas washed with water and dried over anhydrous magnesium sulfate. Thesolvent was then distilled off to givedi-4"-(1-hydroxyethyl)-4-octylterphenyl as a white solid.

19.3 g of this white solid was dissolved in 200 ml of drydichloromethane, to which 20 ml of pyridine was added and then asolution of 4.7 g of acetyl chloride in 50 ml of dichloromethane wasadded dropwise at room temperature. About 2 hours later, the reactionsolution was poured into 200 ml of 3N hydrochloric acid and extracted.The organic layer was washed with water and then with a 7% sodiumhydrogencarbonate solution successively and thereafter dried overanhydrous magnesium sulfate.

The solvent was distilled off and the resulting white solid wasrecrystallized from ethanol to give 18.0 g ofdl-4"-(1-acetoxyethyl)-4-octylterphenyl in an 84% yield.

A solution of 6.0 g of dl-4"-(1-acetoxyethyl)-4-octylterphenyl in 10 mlof chloroform and 1.0 g of lipase ("Amano P" lipase made by AmonoPharmaceutical Co., Ltd.) were added into 300 ml of a 0.1M phosphatebuffer solution (pH 7) and stirred vigorously at 35° C. for 29 hoursunder nitrogen atmosphere.

The reaction solution was extracted with ethyl acetate. The extract wasconcentrated and purified by column chromatography using achloroform-ethyl acetate mixed solvent to obtain 1.8 g (41% yield) of(+)-4"-(1-hydroxyethyl)-4-octylterphenyl. [α]_(D) ²⁵ =+23.6° (c=1,chloroform); 98% ee; melting point: 242° C. (decomposed).

3.86 g (10 mmol) of (+)-4"-(1-hydroxyethyl)-4-octylterphenyl wasdissolved in a mixed solution of 50 ml of toluene and 50 ml of pyridine,and then 1.9 g (12 mmol) of octanoyl chloride was added at 30°-35° C.The mixture was kept at 40°-50° C. for 2 hours.

After the reaction was completed, 200 ml of water and 200 ml of toluenewere added to the reaction solution. Then the liquid phase was separatedand the organic layer was washed with a 3N hydrochloric acid solution,water, a 5% sodium bicarbonate solution and water in that ordersuccessively.

The organic layer was concentrated under reduced pressure and purifiedby column chromatography to obtain 5.0 g (98% yield) of(+)-4-(1-octanoyloxyethyl)-4"-octylterphenyl. [α]_(D) ²⁵ =+62°.

EXAMPLE 72

The procedure of Example 71 was followed except for the replacement of4"-acetyl-4-octylterphenyl with 4"-acetyl-4-pentylterphenyl to obtaindl-4"-(1-acetoxyethyl)-4-pentylterphenyl. This was further treatedaccording to Example 71 to obtain the results shown in Table 5.

                                      TABLE 5                                     __________________________________________________________________________                             Objective compound                                                     Acylating    Optical                                                                            Yield                                     Example                                                                            A     X  l m reagent                                                                              R     rotation*                                                                          (%)                                       __________________________________________________________________________    69   C.sub.5 H.sub.11 O--                                                                --**                                                                             1 1 C.sub.8 H.sub.17 COCl                                                                --C.sub.8 H.sub.17 CO                                                               +68°                                                                        98                                        70   C.sub.8 H.sub.17 O--                                                                --**                                                                             1 1 "      "     +65°                                                                        98                                        72   C.sub.5 H.sub.11 --                                                                 --**                                                                             2 1 "      "     +63°                                                                        97                                        __________________________________________________________________________     *c = 1, chloroform                                                            **n = 0                                                                  

EXAMPLE 73

The procedure of Example 15 was followed except that hexanoyl chloridewas used in place of acetyl chloride to obtain hexanoic ester of(+)-p-benzyloxy-1-phenethyl alcohol. [α]_(D) ²⁵ =+73° (c=1, CHCl₃);n_(D) ²⁵ : 1.5289.

EXAMPLE 74

The procedure of Example 19 was followed except that octanoyl chloridewas used in place of acetyl chloride to obtain(+)-4-benzyloxy-4'-(1-octanoyloxyethyl)biphenyl. [α]_(D) ²⁵ =+43° (c=1,CHCl₃); melting point: 91°-92° C.

In Table 6 below are shown the measured values of spontaneouspolarization of the compounds which presented an Sc* phase. The measuredvalues shown are those determined at a temperature 10° C. below theupper phase transition temperature of Sc*. The measured values ofspontaneous polarization of these compounds were all above 100 nC/cm²,and especially that of the compound of Example 30 was over 200 nC/cm².

                  TABLE 6                                                         ______________________________________                                        Optically active Spontaneous                                                  benzene derivatives (I)                                                                        polarization (nC/cm.sup.2)                                   ______________________________________                                        (Example No.)                                                                 30               208                                                          34               165                                                          35               170                                                          52               150                                                          56               173                                                          58               131                                                          ______________________________________                                    

EXAMPLE 75 (Application)

The following three liquid crystal compounds were mixed in the specifiedmolar ratios by heating and melting them to prepare a liquid crystalcomposition. ##STR47##

This liquid crystal composition presented a chiral smectic (Sc*) phaseat temperatures below 38° C. and showed spontaneous polarization of 40nC/cm² at 25° C.

On the other hand, the equimolar mixture of the above two knowncompounds presented an Sc* phase at temperatures below 35° C. and showedspontaneous polarization of only 4 nC/cm². It was thus clarified thatthe use of the compounds of this invention can realize a hike of theupper limit of the temperature range in which a chiral smectic phaseappears in the known compounds and an enlargement of spontaneouspolarization.

PRODUCTION OF LIQUID CRYSTAL ELEMENT

Two glass substrates provided with transparent indium oxide electrodeswere coated with a polyimide high-molecular film and lapped with a gauzein a given direction. A liquid crystal cell was assembled therewith byusing glass fibers (6 μm in diameter) as spacer so that the lappingdirections on the two substrates would become parallel to each other,and said liquid crystal composition was vacuum-encapsulated therein toform a liquid crystal element.

This liquid crystal element was disposed between two polarizers arrangedto cross each other at right angles and an electric field was appliedthereto. A change of intensity of transmitted light was observed onapplication of 20 V.

The response time as determined from such change of intensity oftransmitted light was about 0.5 ms, and the contrast was 1:20.

The compounds of this invention which presented no Sc* phase (see Table7 below) were combined with said known compounds to prepare thecompositions in the same way as in said Application Example 75 and theirspontaneous polarization was measured. Shown in Table 7 are the valuesof spontaneous polarization of the compositions made by blending saidcompounds of this invention in an amount of 20% by mole with the twoknow compounds (base liquid crystal). These results show that thecompounds of this invention which present no Sc* phase by themselves arealso effective for enlarging spontaneous polarization (P_(S)) of theirmixed compositions with known compounds. It was also ascertained thatthe compound of Example 23, which is a bicyclic compound, could providea large value of spontaneous polarization.

                  TABLE 7                                                         ______________________________________                                        Blend             P.sub.S (nC/cm.sup.2)                                       ______________________________________                                        Compound of Example                                                           29                26                                                          26                28                                                          41                32                                                          46                39                                                          31                33                                                          23                25                                                          ______________________________________                                    

What is claimed is:
 1. An optically active benzene derivativerepresented by the formula: ##STR48## wherein A represents alkyl oralkoxy having 1 to 15 carbon atoms; R° represents a hydrogen atom or--COR in which R represents alkyl having 2 to 14 carbon atoms; and *indicates an asymmetric carbon atom.